Bobbin case of rotary shuttle device for sewing machine

ABSTRACT

Disclosed is a bobbin case of a rotary shuttle device for a sewing machine, in which an under thread pulled out of a bobbin is continuously and stably supplied to a sewing region. The bobbin case comprises a main body integrally provided with a body, and a side portion which is bent downward at a side of the body to have a thick portion at which a fixing hole and adjusting hole is formed and a think portion at which a first and second supporting portion and a supporting piece for supporting and guiding the under thread are formed, the first and second supporting portions being divided by a boundary portion which is formed with a discharging hole for discharging the under thread pulled out of a bobbin from an inner portion of the side portion to an outside; and a guide member formed with a coupling hole and a controlling hole which is corresponding to the fixing hole and the adjusting hole and through which a fastening bolt and a controlling bolt are releasably screwed, wherein one end of the guide member is also formed with a first fixing piece and a second fixing piece which are respectively fixedly inserted into the first and second supporting hole formed at the side portion of the main body, and the second fixing piece forms a path, through which the under thread is passed, together with the supporting piece.

TECHNICAL FIELD

The present invention relates to a sewing machine, and moreparticularly, a bobbin case of a rotary shuttle device for a sewingmachine, which continuously and stably guides and supplies an underthread pulled out of bobbin to a sewing region.

BACKGROUND ART

Generally, an embroidery, domestic or industrial sewing machine, asshown in FIG. 1, has a rotary shuttle device for supplying an underthread. The rotary shuttle device comprises an outer shuttle which isdisposed at a driving shaft 1 rotatably connected to a power generatingunit, an inner shuttle 3 which is received in the outer shuttle 2, abobbin 4 which is received in the inner shuttle 3 and on which the underthread is wound, and a bobbin case 5 for receiving the bobbin 4.Recently, in order to wind a large amount of the under thread on thebobbin 4, the bobbin 4 is provided with sidewalls 4 a, 4 b respectivelyformed at both ends thereof and a partition wall 4 c formed between thesidewalls 4 a, 4 b to have a trough portion. According to a constructionof the rotary shuttle device as described above, when performing asewing operation, the outer and inner shuttles 2, 3 are relativelyrotated, and at the same time, the under thread wound on the bobbin 4 ispulled out and supplied through the bobbin case 5 and the outer shuttle2 to a lower portion of cloth to be sewn. Then, the under thread is sewninto the cloth in cooperation with an upper thread supplied from anupper portion of the cloth. At this time, the bobbin case 5 guides theunder thread pulled out of the bobbin 4 to the outer shuttle 3 or asewing region.

As shown in FIG. 2, the bobbin case 5 is comprised of a main body 7having a discharging hole 6 for discharging the under thread pulled outof the bobbin 4, and a guide member 8 which is formed in the shape of aleaf spring type to guide the under thread discharged through thedischarging hole 6 of the main body 7 and also prevent separation of theunder thread. Meanwhile, the main body 7 is further formed with acircular through hole 7 a, a rectangular supporting hole 7 b, a fixinghole 7 c and an adjusting hole 7 d. Corresponding to the holes of themain body 7, at a front end side of the guide member 8, there are formeda first supporting piece 8 a inserted into the through hole 7 a of themain body 7 and a second supporting piece 8 b inserted into thesupporting hole 7 b, and also at a rear end side of the guide member 8,there are formed a coupling hole 8 c for fixing the guide member 8 tothe main body 7 and a controlling hole 8 d formed to be adjacent to thecoupling hole 8 c to adjust elastic force of the guide member 8. Inaddition, between the constructing portions as described above, there isformed a guide groove for guiding the under thread. Of course, afastening bolt 9 a is fastened through the coupling hole 8 c into thefixing hole 7 c. A controlling bolt 9 b is also screwed into thecontrolling hole 8 d. Then, the controlling bolt is tightened orloosened to properly control the elastic force of the guide member 8. Incase the bobbin is used in the embroidery sewing machine, an outlet portmay be formed at a proper place of the main body 7 so that the underthread can substantially get out of the main body 7. Further, at thedischarging hole 6 of the main body 7 is formed a “” shaped groove 6 afor guiding the under thread to the discharging hole 6.

According to the construction as described above, the under threadpulled out of the bobbin 4 goes out of the discharging hole 6 of themain body 7 and passes between a side portion of the main body 7 and theguide member 8, or is then supplied through the outlet port formed atthe main body to the outer shuttle 2. At this time, the under threadsubstantially gets out of the outlet port (not shown) via a guide troughbetween the first supporting piece 8 a and the second supporting piece 8b of the guide member 8.

However, the bobbin case constructed as above causes various problems asfollows. First, since the under thread pulled out through thedischarging hole 6 of the main body 7 is positioned within a range ofthe partition wall of the bobbin 4 which is rotated at a high speed inthe main body 7, the under thread is damaged, and in the worst case, cutby the partition wall.

Secondly, since the guide trough formed among the constructing portionsof the guide member has a wide guide region, a moving and fluctuatingextent of the under thread is increased. Therefore, there is a problemthat the under thread is not precisely and stably supplied to the outletportion of the main body.

Thirdly, the under thread pulled out of the bobbin 4 cannot maintainsproper tensile force due to the above problems. Further, intermittentphenomenon and intermittent sound are generated when supplying the underthread, thereby lowering the quantity of sewn products and also reducingstillness in an operation of the sewing machine.

Additionally, a groove for inserting the under thread into thedischarging hole is curved. Therefore, there is other problem that it isdifficult to insert the under thread into the discharging hole.

DISCLOSURE OF THE INVENTION

Therefore, it is an object of the present invention to provide a bobbincase of a rotary shuttle device for a sewing machine, which is capableof preventing damage or cut of a under thread passing through a mainbody from a bobbin.

It is other object of the present invention to provide a bobbin case ofa rotary shuttle device for a sewing machine, which is capable ofdeviating the under thread passing through a discharging hole of themain body from the range of a partition wall of a bobbin rotated in themain body.

It is another object of the present invention to provide a bobbin caseof a rotary shuttle device for a sewing machine, by which the underthread is pulled out of a bobbin through an optical region of a guidemember, while maintaining optical tensile force.

It is yet another object of the present invention to provide a bobbincase of a rotary shuttle device for a sewing machine, in which the underthread can be stably supplied and the sewing machine can be silentlyoperated, thereby increasing the quality of sewn products.

It is yet another object of the present invention to provide a bobbincase of a rotary shuttle device for a sewing machine, which is capableof facilely inserting one end of the under thread wound on the bobbininto the discharging hole.

To accomplish the above objects and advantages, there is provided abobbin case of a rotary shuttle device for a sewing machine, in which abobbin for winding an under thread is rotatably disposed, comprising amain body integrally provided with a body, and a side portion which isbent downward at a side of the body to have a thick portion at which afixing hole and adjusting hole is formed and a think portion at which afirst and second supporting portion and a supporting piece forsupporting and guiding the under thread are formed, the first and secondsupporting portions being divided by a boundary portion which is formedwith a discharging hole for discharging the under thread pulled out of abobbin from an inner portion of the side portion to an outside; and aguide member formed with a coupling hole and a controlling hole which iscorresponding to the fixing hole and the adjusting hole and throughwhich a fastening bolt and a controlling bolt are releasably screwed,wherein one end of the guide member is also formed with a first fixingpiece and a second fixing piece which are respectively fixedly insertedinto the first and second supporting hole formed at the side portion ofthe main body, and the second fixing piece forms a path, through whichthe under thread is passed, together with the supporting piece.

BRIEF DESCRIPTION OF THE DRAWINGS

The above object, other features and advantages of the present inventionwill become more apparent by describing the preferred embodiment thereofwith reference to the accompanying drawings, in which:

FIG. 1 is an exploded perspective view of a conventional rotary shuttledevice for a sewing machine;

FIG. 2 is an exploded perspective view of a bobbin case of a rotaryshuttle device for a sewing machine of FIG. 1;

FIG. 3 is an exploded perspective view of a bobbin case of an outershuttle of the rotary shuttle device according to the present invention;

FIG. 4 is a partially cut away view of a portion of a main body of thebobbin case in FIG. 3;

FIGS. 5a and 5 b are partially enlarged views showing a state that anunder thread is discharged through the assembled bobbin case accordingto the present invention;

FIG. 6 is a side view of a discharging hole of the bobbin case accordingto other embodiment of the present invention;

FIG. 7 is a partially cut away view of the main body of the bobbin caseaccording to another embodiment of the present invention; and

FIGS. 8a and 8 b are partially enlarged views showing a state that theunder thread is discharged through the assembled bobbin case in FIG. 7.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, preferred embodiments of the present invention will be described indetail with reference to the annexed drawings.

Referring to FIGS. 3 and 4, a bobbin case of a rotary shuttle deviceaccording to the present invention basically comprises a main body 10 inwhich a bobbin is rotatably disposed, and a guide member 12 for guidingan under thread pulled out of the bobbin in the main body 10.

The main body 10 is integrally provided with a body portion 16 that isformed in the shape of a circular plate on the whole and has a gripportion 14 pivotally disposed on the body portion 16, and a side portion18 that is extended downward at a portion of the body portion 16 to havea desired length. Particularly, the side portion 18 is formed with athick portion 18 a and a thin portion 18 b for workability and stiffnessthereof. The thick portion 18 a and the thin portion 18 b are divided bya boundary portion 18 c. The boundary portion 18 c is formed in theshape of a step portion due to a difference in thickness or heightbetween the thick portion 18 a and the thin portion 18 b. Meanwhile,even though not shown in figures, those skilled in the art willappreciate that an embroidery sewing machine has an outlet port throughwhich the under thread of the main body is passed.

At the thick portion 18 a of the side portion 18, there are formed afixing hole 22 for fixing the guide member 12 using a fastening bolt 20,and an adjusting hole 26 in which a controlling bolt 24 for controllingelastic force of the guide member 12 is fastened. Further, at the thinportion 18 b of the side portion 18, there are formed a first and secondsupporting hole 28, 29 for supporting a fixing piece formed at an end ofthe guide member 12. Particularly, at an end of the thin portion 18 b ofthe side portion 18, there is formed a supporting piece 30 forsupporting and guiding the under thread. The supporting piece 30functions to guide and support the under thread so that the under threadpulled out of the bobbin is passed between the guide member 12 and theside portion 18 and then precisely supplied to a desired sewingposition. Preferably, the second supporting hole 29 and the supportingpiece 30 are identical with an extended line of an outer circumferenceof a partition wall 4 c of the bobbin 4, and further the supportingpiece 30 is formed by vertically and horizontally cutting an end of thethin portion 18 b and then bending the cut end of the thin portion 18 b.Therefore, between the second fixing piece of the guide member 12 andthe supporting piece 30 formed at the thin portion 18 b of the sideportion 18 of the main body 10, as described below, there is formed ordefined an under thread path. Of course, it is preferred that both sidesof the supporting piece 30 is rounded so that the under thread issmoothly passed.

Meanwhile, the boundary portion 18 c of the side portion 18 is formedwith a discharging hole 32 through which the under thread pulled out ofthe bobbin is discharged from an inner portion of the side portion 18 toan outside. Particularly, as shown, in FIG. 4, the discharging hole 32formed at the boundary portion 18 c of the side portion 18 of the mainbody 10 is formed with two discharging openings so as to discharge theunder thread without any damage or cut of the under thread. That is, atboth sides of the discharging hole 32, there are formed a firstdischarging opening 34 and a second discharging opening 36 correspondingto the first discharging opening 34 so that the under thread can beselectively and essentially passed therethrough according to a positionof the under thread pulled out of the bobbin. Preferably, each of thedischarging openings 34, 36 is formed at the boundary portion 18 c orthe thin portion 18 b adjacent to the boundary portion, and further thedischarging openings 34, 36 are symmetrically formed with the partitionwall 4 c of the bobbin 4 in the center.

Particularly, it is preferred that the discharging openings 34, 36,through which the under thread is discharged, is formed to be deviatedfrom a rotating range of the partition wall 4 c of the bobbin 4 so thatthe under thread 34, 36 passing through the discharging opening 34, 36is not contacted with the partition wall 4 c of the rotating bobbin 4,thereby preventing the under thread from being damaged or cut by thepartition wall 4 c of the bobbin 4. Further, it is preferred that eachdischarging opening 34, 36 is rounded or curved so that the under threadis smoothly discharged.

Meanwhile, a guide groove 38 is communicated with the discharging hole32 so as to facilely insert an end of the under thread pulled out of thebobbin at the early stage. Preferably, the guide groove 38 is formed inthe shape of a diagonal line or an oblique line so as to facilely andrapidly insert the under thread through the discharging groove 38 intothe discharging groove 32.

In this embodiment, the discharging openings are formed to diverge eachother. However, those skilled in the art will appreciate that thedischarging openings can be formed in various other shapes so as todeviate from the rotating range of the partition wall of the bobbin. Forexample, in case of a bobbin in which the partition wall is not formedat a center portion thereof, as shown in FIG. 6, the discharging hole 32may be formed in the shape of a linear line or an elongated hole.

Referring to FIG. 3, the guide member 12 is basically formed with acoupling hole 40 and a controlling hole 42 which is corresponding to thefixing hole 22 and the adjusting hole 26 and through which a fasteningbolt 20 and a controlling bolt 24 are releasably screwed. At one end ofthe guide member 12, there are formed a first fixing piece 44 which isfixedly inserted into the first supporting hole 28 formed at the sideportion of the main body 10 and a second fixing piece 45 which isfixedly inserted into the second supporting hole 29, thereby preventingseparation of the guide member 12 from the main body 10. Further, thefirst fixing piece 44 restricts a range that the under thread is pulledout or a part of the range together with the supporting piece 30.

FIG. 7 is a partially enlarged perspective view of the main body of thebobbin case according to other embodiment of the present invention. Thesupporting piece 30 for supporting the under thread is integrally formedwith the first supporting hole 28. One end of the supporting piece 30 ispositioned at the same distance from the first and second dischargingopenings 34, 36. Meanwhile, the guide member 12 is closely contactedwith an outer face of the supporting piece 30 to form a space throughwhich the under thread is passed. In this case, it is preferred that thesupporting piece 30 is formed at a position of the first supporting hole28 by an embossing process.

Hereinafter, an operating mode of the bobbin case of the rotary shuttledevice for the sewing machine according to the present invention will bedescribed fully.

For example, if a user operates the sewing machine to perform a sewingoperation, the under thread pulled out of the bobbin 4 of the rotaryshuttle is discharged through the discharging hole 32 of the main body10. At this time, the under thread passing through the discharging hole32 is discharged through the first discharging opening 34 or the seconddischarging opening 36 according to a position that the under thread ispulled out of the bobbin 4. Therefore, the under thread is deviated fromthe rotating range of the partition wall 4 c so as to prevent the underthread from being contacted with the partition wall 4 c and thuscompletely prevent the damage or cut of the under thread.

In more detail, in case the under thread is discharged from a windingportion of the bobbin 4, which has a relatively large area, the underthread T is discharged through only the first discharging opening 34 ofthe discharging hole 32 (referring to FIG. 5a). On the contrary, in casethe under thread is discharged from the winding portion having arelatively small area, the under thread T is discharged through only thesecond discharging opening 36 of the discharging hole 32 (referring toFIG. 5b).

In addition, the under thread, which is discharged through one of thedischarging openings of the discharging hole 32, passes between theguide member 12 and the thin portion 18 b of the side portion 18 of themain body 10 and gets out through a under thread path formed between thesecond fixing piece 45 of the guide member 12 and the thin portion 18 bof the side portion of the main body 10. At this time, since the underthread is discharged through only a range of the under thread path or arange of the under thread path defined by the fixing piece and thesupporting piece, the under thread is linearly discharged (a solid line)or discharged at an optimal inclined angle (a dotted line) toward thesewing region, whereby the under thread has always constant tensileforce while being supplied. Moreover, since the first supporting hole 29and the supporting piece 30 are placed to be identical with the extendedline of the outer circumference of the partition wall 4 c of the bobbin4, and positioned at the same distance from the first and seconddischarging openings 34, 36, the tensile force applied to the underthread is constantly maintained. Accordingly, the under thread can befreely moved between the first and second discharging openings 34, 36.The tensile force of the under thread can be properly adjusted bycontrolling the elastic force of the guide member 12 using thecontrolling bolt 24.

Meanwhile, an operation of the bobbin case of the rotary shuttle devicefor the sewing machine 20 according to another embodiment of the presentinvention is described in detail.

FIGS. 8a and 8 b are partially enlarged views showing a state that theunder thread is discharged through the assembled bobbin case in FIG. 7.The under thread T passed through the discharging opening of thedischarging hole 32 gets out at a desired discharging angle θ through apath formed between the second fixing piece 45 of the guide member 12and the supporting piece 30 formed at the thin portion 18 b of the sideportion 18 in the embossed shape. At this time, one side of thesupporting piece 30 is identical with the extended line of the outercircumference of the partition wall 4 c of the bobbin 4, and ispositioned at the same distance from the first and second dischargingopening 34, 36 so as to always maintain the constant tensile forceregardless of the position of the under thread. In this embodiment,since the discharging angle θ is smaller than that of other embodimentsas well as a conventional bobbin case, the tensile force applied to theunder thread T is reduced, thereby preventing the under thread T frombeing cut. Further, since the path of the under thread T is tightlyclosed by the space formed by the thin portion 18 b and the guide member12 and the space formed by the supporting piece 30 and the second fixingpiece 45, it is also prevented that the under thread is separated.

Thus, the under thread pulled out of the bobbin is discharged throughthe bobbin case with an optimal direction and tensile force beingmaintained, and then supplied to the sewing region, thereby facilelyperforming the sewing operation.

According to the bobbin case of the rotary shuttle device for the sewingmachine of the present invention, when the under thread wound on thebobbin is discharged, it is prevented that the under thread is contactedwith the partition wall of the bobbin and the under thread is damaged orcut. Further, the under thread is discharged through the under threadpath defined between the limited fixing piece of the guide member andthe supporting piece and then always supplied in the optimal directionand tensile force.

While the present invention has been described in detail, those skilledin the art will appreciate that various modifications and substitutionscan be made thereto without departing from the spirit and scope of thepresent invention as set forth in the appended claims.

What is claimed is:
 1. A bobbin case of a rotary shuttle device for asewing machine, in which a bobbin for winding an under thread isrotatably disposed, comprising; a main body integrally provided with abody, and a side portion downwardly bent at a side of the body to form athick portion at which a fixing hole and an adjusting hole is formed,and a thick portion at which a first and second supporting hole and asupporting piece for supporting and guiding the under thread are formed,the first and second supporting portions being divided by a boundaryportion which is formed with a discharging hole for discharging theunder thread pulled out of a bobbin from an inner portion of the sideportion to an outside; a guide member formed with a coupling hole and acontrolling hole which corresponds to the fixing hole and the adjustinghole and through which a fastening bolt and a controlling bolt arereleasably screwed, wherein one end of the guide member is also formedwith a first fixing piece and a second fixing piece which arerespectively fixedly inserted into the first and second supporting holeformed at the side portion of the main body, and the second fixing pieceforms a path, through which the under thread is passed, together withthe supporting piece and wherein the discharging hole is formed with afirst discharging opening and a second discharging opening through whichthe under thread pulled out of the bobbin is selectively passedaccording to a position of the under thread.
 2. The bobbin case of claim1, wherein the discharging openings of the discharging hole is formed atthe boundary portion of the side portion, while keeping a distance fromthe guide member.
 3. The bobbin case of claim 1, wherein each of thedischarging openings is disposed to be deviated from a rotating range ofthe partition wall if the bobbin is disposed in the main body and hasthe partition wall.
 4. The bobbin case of claim 1, wherein thedischarging hole is communicated with a guide groove which is diagonallyformed from a side of the thick portion to a center portion of thedischarging hole so as to insert an end of the under thread into thedischarging hole at an early stage.
 5. The bobbin case of claim 1,wherein a side end of the supporting piece, through which the underthread is passed, is positioned at the same distance from the first andsecond discharging opening.
 6. A bobbin case of a rotary shuttle devicefor a sewing machine, in which a bobbin for winding an under thread isrotatably disposed, comprising; a main body integrally provided with abody, and a side portion downwardly bent at a side of the body to form athick portion at which a fixing hole and an adjusting hole is formed,and a thick portion at which a first and second supporting hole and asupporting piece for supporting and guiding the under thread are formed,the first and second supporting portions being divided by a boundaryportion which is formed with a discharging hole for discharging theunder thread pulled out of a bobbin from an inner portion of the sideportion to an outside; a guide member formed with a coupling hole and acontrolling hole which corresponds to the fixing hole and the adjustinghole and through which a fastening bolt and a controlling bolt arereleasably screwed, wherein one end of the guide member is also formedwith a first fixing piece and a second fixing piece which arerespectively fixedly inserted into the first and second supporting holeformed at the side portion of the main body, and the second fixing pieceforms a path, through which the under thread is passed, together withthe supporting piece and wherein the discharging hole is formed in theshape of an elongated hole.
 7. A bobbin case of a rotary shuttle devicefor a sewing machine, in which a bobbin for winding an under thread isrotatably disposed, comprising; a main body integrally provided with abody, and a side portion downwardly bent at a side of the body to form athick portion at which a fixing hole and an adjusting hole is formed,and a thick portion at which a first and second supporting hole and asupporting piece for supporting and guiding the under thread are formed,the first and second supporting portions being divided by a boundaryportion which is formed with a discharging hole for discharging theunder thread pulled out of a bobbin from an inner portion of the sideportion to an outside; a guide member formed with a coupling hole and acontrolling hole which corresponds to the fixing hole and the adjustinghole and through which a fastening bolt and a controlling bolt arereleasably screwed, wherein one end of the guide member is also formedwith a first fixing piece and a second fixing piece which arerespectively fixedly inserted into the first and second supporting holeformed at the side portion of the main body, and the second fixing pieceforms a path, through which the under thread is passed, together withthe supporting piece and wherein the supporting piece is integrallyformed with the first supporting hole, and closely contacted with a sideof the guide member.